Triaxial Test Equipment
Triaxial test equipment is used for shear strength testing on soil specimens. Triaxial shear strength is one of the most versatile soil strength tests in geotechnical engineering. More complex than a direct shear test, it allows control of specimen stresses in perpendicular directions. Drainage in the sample can also be controlled and specimen pore pressure can be monitored.
Test specimens may be obtained from an undisturbed sample or prepared as remolded samples. The specimen is sheathed in a protective latex membrane and placed inside a fluid-pressurized chamber, which is then attached to a Load Frame. The sample is vertically loaded and sheared while keeping the rate of axial deformation constant. These tests determine the strength and the stress-strain relationship of the soil.
There are several different types of triaxial compression tests: Consolidated-Drained (CD) is performed according to the ASTM D7181 standard test method, Consolidated-Undrained (CU) is implemented using the ASTM D4767 method, and Unconsolidated-Undrained (UU) is performed according to the ASTM D2850 testing procedure. In the CD test, the sample is allowed to drain, whereas the CU and UU tests are performed on a sample that remains undrained. Samples in the CD and CU tests are allowed to consolidate or adjust, during the test. In the UU test, loads are applied quickly and the sample remains unconsolidated.
Click here for a Triaxial/Permeability basic setup diagram.
- Triaxial Cells are made of heavy clear acrylic for maximum visibility and contain the specimen and the cell fluid during testing. Cells include precision ball valves and brass fittings, and a stainless steel loading piston operating through an internally lubed U-cup.
- Triaxial Cell Accessories include Caps and Pedestals for a wide range of sample diameters popular in the soil testing industry. Also featured here are popular sizes of Latex Membranes, Porous Stones, and O-Rings to fit the samples, along with devices to aid in their installation. Check out the Latex Membranes and Porous Stones pages for complete selections.
- Triaxial / Permeability Control Panels allow operators to monitor and control air and fluid pressures in the Triaxial Chambers for filling, saturation, testing, and draining. The Master Control Panel with digital pressure readout is used for a single test chamber and the Add-on Control Panel is ideal for adding additional test chambers.
- Load Frames by Karol-Warner are designed to accommodate a range of strain rates and loading capacities for a variety of triaxial tests. A Triaxial Load Frame can be outfitted with a wide selection of test-specific components for improved versatility. The Load Frames also allow for quick adjustment of height so that testing fixtures for popular soil tests are easily interchangeable.
- Triaxial Data Acquisition Software records specimen information and real-time test data, calculates results, then prepares reports following ASTM and AASHTO requirements. Additional components are required for operation.
- Load & Displacement Measurement components measure the stress and strain of the sample throughout the test. Mechanical or digital measurement components mount easily to Load Frames or testing fixtures. Choose digital components if data recording or acquisition is required.
- Sample Preparation includes equipment for trimming, preparing, and mounting samples to ensure accurate testing.
